Finally figured out noise in diff on my 2015 ZL1

[mixitup]

On the higher back lash (.017 - .019) the ring gear pattern has moved further back to the heel. On the teeth with .004 backlash the pattern is closer to the toe. I can't feel wear on the ring gear, however I have not checked the pinion gear yet.

[mixitup]

I have finally disassembled the complete carrier. To remove the right side (passenger side) clutch pack the round shaped block that has the 4 spider gears that puts pressure down onto the bellville washer and clutch pack has to be removed. It is all held together with 3 roll/spring pins that cannot be punched through. I had to drill them out with cobalt drill bits. This took me approximately 40 minutes.

Once the roll pins are removed I had to slightly compress the round block in my press to be able to push out the pins that the spider gears rotate on.

I am absolutely appalled by the design of the differential by AAM and the fact that GM approved this design. This was designed as a throw away unit.

There are no parts available, only the gears, seals, pinion nut, shim kits from ebay. Dealers have nothing, not even a pinion nut.

FYI the teeth count on the friction plate is 45. The closest part I found was from Dana diff that has 43 teeth (which you can't install).

I brought the carrier to a local machine shop yesterday. They will attempt to machine the face of the carrier that the gear mounts to because it has .013 runout.

I will keep you posted...

[70T/A400]

I am glad you are getting to the bottom of your problem

This will help all of us in the future

If you think an American company has quality standards, you are now waking up and realizing they have other priorities. They build cars to a price point.

Keep us up to date with your progress.

[roh]

Thanks for blazing the trail for the rest of us.

[Whisper1]

This is all new to me and I've had my 2012 since 2014 when I purchased it with 7K miles. Reason I bought the car is after researching a bit I had read that the transmission and rear end were bullet proof. The claim from a GM engineer was that they had made roughly 600 passes down the drag strip without any rear end issue. Way back 14 years ago independent rear ends were notoriously weak so it was supposed to be better than most.
Anyway, I have seen mulitple cars in 2012-2013 make a boatload of passes without issue.
I hear you on the whine. Mine is whisper quiet at 30K miles so I'll keep my fingers crossed. Not an IRS, but I had a Moser 9" in my F body. Took me two tries from the factory as the first unit howled at an ear splitting level. Even the "good" one I recieved still had a fair amount of whine and it also leaked fluid. Local performance shop owner said the Moser could be guaranteed to whine and leak fluid. But, they were durable. Anyway, distressing to hear about yet another parts issue. I just assumed the rear end could be swapped with an aftermarket unit but I'm hearing no? Thanks for diving into this.

[mixitup]

Well I finally received all my parts. The hold up was waiting for the special 5mm X 32mm "S" coiled roll pins (3 have to be installed to hold the pinion shaft and gears). I've been waiting 7 weeks for them. I'm going to include pics of the clutch pack that I have wiped clean and pinion shaft and gears.

I will start to re-install everything into the carrier this weekend and video it. Will try and make in in depth. I will post all measurement, clutch pack stack heights, bearing part numbers etc...

I just finished making set up pinion bearings for the pinion gear. Just an FYI, the outer pinion bearing is the same part number as a inner pinion bearing on a 12bolt diff.

[mixitup]

Clutch pack pressure is achieved by use of a Bellville washer. These washers are also used in C5, C6 diffs. Here's a pic showing the comparison of a smaller C6 Z06 washer compared to what is used the this ZL1 diff. Huge difference in size. I also rebuild C5 and C6 diffs.

[mixitup]

The friction plates are 45 tooth. The closest tooth count I can find are from Dana diff which use 43 tooth frictions (which we still can't use) As of now, I cannot locate any of the clutch pack parts anywhere. If your clutch packs are worn, we're shit out of luck.